Plants had been used from prehistoric times for various usages; from culinary as herbs and spices, defense against insects, fungi and herbivorous mammals and to treat diseases. Plants make many chemical compounds and there are over 12,000 active compounds are known to science. These chemical can work on the human body and can act exactly the same way as pharmaceutical drugs, however, the effects of taking a plant as medicine can be quite complex as a single plant may contain many substances. It may be beneficial and it can also cause harmful side effects.
Throughout the history, there were many medicinal plants were recorded to have a certain effects on certain diseases. Some of these plants are still being used in traditional recipes and some plants had already gone research to find the active compound responsible in treating the diseases respectively. These traditional recipes can be classified according to their region, for example, plants used in traditional African medicine, in Ayurveda, in traditional Chinese medicine, in traditional Māori medicine and in traditional Native American disease.
There are a large number of medicinal and aromatic plants which are used for medicinal and aromatic purposes. Medicinal plants are sometimes used for aromatic purposes similarly aromatic plants may also be used for medicinal purpose thus classifying a certain plants can be quite difficult. Generally, it can be classified according to their growth habit. It may be a tree, shrub, herb, annuals, biennial, tubers, rhizomes and climbers.
These plants can also be classified according to their active phytochemical compounds such as an alkaloids, glycosides, polyphenols and terpenes. Phytochemicals are non-nutritive plant chemicals that have protective or disease preventive properties. They are non-essential nutrients, meaning that they are not required by the human body for sustaining life.
Alkaloids are known as bitter-tasting chemicals and often toxic. It is very widespread in nature and most occur in herbaceous dicots and fungi. It can have diverse effects but the most pronounced are on the nervous system.
Glycosides have sugar molecule (glyco-) attached to the active component of the compound. Generally, it is categorized by their active component: cyanogenic glycosides, cardiac glycosides, and saponins.
Polyphenols of several classes are widespread in plants. They include the colourful anthocyanins, hormone-mimicking phytoestrogens, and astringent tannins. Plants containing phytoestrogens have been used for centuries to treat gynaecological disorders such as fertility, menstrual, and menopausal problems.
Terpenes and terpenoids of many kinds are found in resinous plants such as the conifers. They are strongly aromatic and serve to repel herbivores. Their scent makes them useful in essential oils, whether for perfumes such as rose and lavender, or for aromatherapy.
Phytochemicals. Retrieved May 11, 2017, from http://www.phytochemicals.info/
Retrieved May 11, 2017, from http://agriinfo.in/default.aspx?page=topic&superid=2&topicid=1409
Seigler, D. S. (2003, October). Medicinal Plants. Retrieved May 11, 2017, from http://www.life.illinois.edu/ib/363/MEDPLANT.html